Pyonkichi

A frog who is crushed by Hiroshi, but his spirit lives on as a talking frog on his shirt, becoming a Flat Surface Frog (平面ガエル Heimen Gaeru). Because said shirt is Hiroshi's only good shirt, he is always forced to travel around and interact with Hiroshi. They are equally obstinate and gluttonous and are always arguing like siblings. He is capable of jumping around and forcing Hiroshi to come along with him.

(Source: Wikipedia)